A)Families with cars
B)American's heavy dependence on cars.
C)Roads and highways.
D)Traffic problems in America.
原文：
W: You Americans are funny. It seems as if you were married to your cars.
M: Yeah, I guess that's true. The country is becoming one big highway. I was reading that there are about 4 million miles of roads and highways in this country now.
Q: What are they talking about?